The invention relates to the detachable connection of a tool, workpiece or gauge holder to the nose of a machine tool spindle. In order to achieve short re-setting times on modern precision machine tools of high output performance, the interface points between the machine and the holders of the workpiece specific cutting tools, gauges or workpieces must be designed such that a change-over can be carried out in the shortest possible time and with maximum positioning accuracy either manually or automatically, whilst the connection must have the rigidity and capacity of transmission for the occurring forces and torques.
An interface that fulfils these requirements to a high degree is the flange connection with centring taper and flange location of the kind described in DIN 55026 or 55028. It is formed by the short female and male taper on the flange of the tool or workpiece holder and on the spindle nose respectively for the radial centring, and by the flange faces at right angles to the axis of rotation of the spindle for the facial alignment of the tool or workpiece holder relative to the spindle, which are brought to bear against each other on assembly by way of bolts or other means of fixture. In order to assure a positive seating in the radial direction, the male taper (spigot) of the spindle nose is of a slightly larger dimension than the female taper of the tool or workpiece holder, so that as the flanges are pulled together the play between the tapered ends is eliminated and the latter are subjected to a slight radial elastic deformation.
A disadvantage of this connection lies in the high manufacturing accuracy which must be observed in order to assure the positioning accuracy and rigidity of the connection. If the close tolerances of the taper angle and taper diameter are transgressed, there is danger of radial and axial errors due to radial play between the male and female tapers, or due to inadequate axial contact between the flanges. If an attempt is made to nevertheless bring the flange faces into contactxe2x80x94by excessive tightening of the fixture bolts for examplexe2x80x94then there is a danger of elastically deforming the spindle nose, which can jeopardise the true running of the spindle. Moreover in the case of frequent assembly and dismantling, a too high pressure of contact on the centring taper risks premature wear and a loss of positioning accuracy.
The object of the invention is to introduce a connection with which the high positioning accuracy and rigidity of the flange connection can always be assured without the risk of undesirable elastic deformation, even in the case of wide manufacturing tolerances and hence low manufacturing costs of the flange components, and premature wear can be avoided. The objective is attained by way of the characteristic features in accordance with the claims.